The invention relates to an apparatus for preshrinking a web material such as woven or knitted fabric. Such apparatus normally is provided with a pressurized steam source which is generally used to dampen the fabric as a preconditioning step prior to treating the web as desired.
A number of different machines have been proposed to effect shrinkage of the fabric. Some of these machines utilize two spaced rolls rotating in opposite directions at different speeds forming a nip into which a fabric is fed. An implement is disposed in the nip area and referred to as a doctor blade and acts to force the fabric into the textured or high friction surface of one of the rolls operating at a faster speed whereby a short columnar length of fabric between the doctor blade and nip is compressed.
Other machinery has also been used to preshrink fabric for example, a shoe has taken the place of the doctor blade. Preshrinking of fabric has been achieved by using a pair of endless belts which are spaced from each other and move in the same linear direction. The belts used are such that the linear speed of the surface of the belt may be changed by varying its thickness in conjunction with creating a curvature of the belt as it moves from the curved surface to the flat surface with the result that when web material fed between the belts is to be longitudinally shrunk the spacing between the belts is increased by decreasing the belt thickness with the result that the surface speed of the belt is being reduced so as to act as a retarding force on the fabric. The curved surface of the belt also cooperates to amplify the shrinkage effect as will be understood by one skilled in the art. Another arrangement for shrinking of fabric comprises a two roll arrangement forming a stuffing chamber in which fabric is shrunk and such arrangement may include a blade member to facilitate the shrinking procedure. Other preshrinking equipment is known which may be fitted with my invention as will be understood from the description which follows.
In most of these arrangements a heat source is provided to condition the fabric prior to the treatment contemplated so as to optimize such treatment.
It is also especially desirable to heat the fabric during treatment in a uniform and controlled fashion and a variety of arrangements exist which can accomplish this beneficial heating of the fabric.
There are steam filled rolls, oil filled rolls and rolls heated with other sources. None known to me are entirely satisfactory since it is not possible without substantial expense to control the uniformity of the heat. This is sometimes accomplished through the use of complex and expensive equipment. The use of added equipment has the obvious drawback of requiring additional space and expense.
It is therefore an object of this invention to provide a preshrinking apparatus already including a source of heat with an apparatus utilizing the source of heat such as steam to heat the fabric in a controlled and uniform fashion.
Another object of this invention is to provide an apparatus for applying heat to a fabric at a controlled temperature which is easy to manufacture and efficient in its operation and economical to make.
For a more complete understanding of the invention and other features and advantages thereof reference should be made to the following detailed description of a preferred embodiment and to the accompanying drawings.